1. Field of the Invention
The present invention relates to slide fasteners with hidden coupling elements, and in particular, to such slide fasteners and their method of manufacture in which the coupling elements are formed in trains connected together by threads.
2. Description of the Prior Art
The prior art is generally cognizant of the invisible-element slide fasteners in which the coupling elements are formed in trains on coupling threads, such as that described in U.S. Pat. No. 3,696,473, wherein the elements are stitched to a folded tape and have projections extending into spaces between the elements to prevent lateral slipping and exposure of the elements. In U.S. Pat. No. 3,855,673, a slide fastener stringer of continuous filament type is disclosed which includes laterally extending barbs to securely contain the knots of two-thread double-locked stitches. U.S. Pat. No. 3,179,996 describes a concealed slide fastener in which a cord carrying the coupling elements is secured to the tape by having the weft threads of the tape extend around the cord and in which two flaps of the tape conceal portions of the elements. Additionally, U.S. Pat. No. 3,068,541 discloses a one sided fastener with scoops molded onto one side of a tape with beads. Illustrations of other types of coupling elements are found in U.S. Pat. Nos. 1,785,240 and 3,302,259.